Carib girl: I have flown in and out of SJU twice this past month. As long as you are in transit and will not be leaving the airport you do not need to present Covid test results or complete a form in advance. On Christmas Eve my connection required me to leave the secure area and pass back through security. The need for that was to go through the USDA luggage scanner as I was re-entering the US from foreign soil. Still no requirement for testing or form advance completion as there is for travellers who are leaving the airport.